Apparatus and method for producing aerated confectionery masses

ABSTRACT

For producing an aerated confectionery mass, a raw confectionery mass is fed at a feed rate from a supply to an aeration unit for introducing gas into the confectionery mass and wherein the aerated confectionery mass is fed to a production line for the production of confectionery or tablets. The feed rate of the raw confectionery mass is controlled such that it corresponds to the demand of the production line, the amount of introduced gas is controlled in response to the feed rate of the confectionery mass so that the aeration level of the confectionery mass remains substantially constant and the temperature of the aeration mass within the aeration unit is controlled such that it remains substantially constant and independent from the feed rate. The aeration unit may include a rotor for stirring and kneading the confectionery mass containing the introduced gas, the rotational speed of the rotor being controlled such that it is enhanced for higher feed rates and reduced for lower feed rates in order to produce gas bubbles of approximately the same size independent from the feed rate. In order to keep the bubble size small during the depositing step, the depositing is realized via a pressurized manifold containing multiple nozzles.

This application is a U.S. national phase application filed under 35 U.S.C. §371 of International application PCT/EP2005/056928, filed on Dec. 19, 2005, designating the United States, which claims the benefit of European Application No. 04106891.7, filed on Dec. 22, 2004, which are hereby incorporated by reference herein.

TECHNICAL FIELD

The invention relates to a method and an apparatus for producing an aerated confectionery mass and in particular a confectionery product. A raw confectionery mass is fed by a feed pump from a supply to an aeration unit wherein the confectionery mass is aerated by introducing gas bubbles into the mass. The aerated mass is then fed to a production line for the production of confectionery or micro-aerated massive tablets.

The confectionery mass is typically a chocolate mass but could also be a filling mass. The chocolate mass is supplied from a mass tank to a tempering unit. In the mass tank the chocolate mass is usually heated to about 45° C. in order to melt all crystals. The chocolate mass is cooled down in the tempering unit to about 25 to 26° C. and then reheated to about 29 to 31° C. in order to melt all crystal structures with exception of the β-structure. The apparatus comprises further a back-pressure regulating valve in an outlet conduit from the aeration unit for adjusting the pressure in the aeration-unit and a depositor hopper into which the aerated mass is fed from the back-pressure valve and from which the mass is dispensed to a downstream production line for manufacturing a desired product. If the product is a tablet it is preferred that the depositor hopper of the production line is replaced by a pressurized manifold comprising multiple nozzles.

BACKGROUND ART

WO 01/30174 discloses a confectionery aeration system of this type, wherein the depositor hopper includes a weir, to return excess chocolate to the mass tank or the tempering unit. Alternatively, the aerated confectionery mass can be re-circulated from the depositor hopper to the aeration unit and back to the depositor hopper and the depositor hopper includes a level probe which controls the supply of fresh confectionery mass via the tempering unit to the aeration unit.

EP 0 724 836 discloses a similar system wherein excess aerated confectionery mass is returned via a restriction valve to the tempering unit and the returned portion of the confectionery mass is de-aerated.

DISCLOSURE OF INVENTION

The problem underlying the invention resides in how to avoid the necessity of de-tempering, de-aeration and re-tempering of the returned portion of the confectionery mass.

This problem is solved according to the invention by controlling the feed rate with which the confectionery mass is fed to the aeration device such that it corresponds to the demand of the production line and cooling the confectionery mass within the aeration device such that the confectionery mass is not heated within the aeration device above a predetermined limit.

The invention makes thus available a one-pass process by which the desired aeration level is achieved in one go. The invention makes possible a continuous aeration operation without the necessity to return any portion of the confectionery mass. A larger amount of energy is saved thereby.

Because the confectionery mass is fed to the aeration device in accordance with the demand of the production line, no portion of the confectionery mass has to be returned. This means that the throughput of the aeration device varies and the heat developed within the aeration device is transferred to a varying amount of confectionery mass. It is therefore necessary to cool the confectionery mass within the aeration device in order to avoid overheating.

The process is carried out usually in such a way that the gas bubbles are rather small so that they are not visible. The gas bubbles can have a size of less than about 50 μm.

The aeration device comprises usually a stator and a rotor between which the confectionery mass and the gas, usually N₂ gas, are introduced. Shearing forces are developed by the rotation of the rotor and the gas bubbles are distributed by the shearing forces within the confectionery mass. The size of the gas bubbles depend on the magnitude of the shearing forces which in turn depend on the constructional details of the aeration device, in particular the distance between stator elements and the rotor elements, as well as on the rotational speed of the rotor. Preferably, the rotational speed of the rotor is controlled such that the bubble size is just below 50 μm. The rotational speed is controlled to be not higher than necessary for producing gas bubbles of the desired size. The energy consumption is lowered thereby. In addition the confectionery mass is heated less with lower rotational speed so that less energy is consumed for cooling the mass.

As mentioned, the feed rate of the aeration device is controlled in response to the demand of the production line. A higher feed rate brings about a higher gas amount and a shorter dwelling time of the confectionery mass within the aeration device. In order to compensate for the shorter dwelling time, it is necessary to enhance the rotational speed of the rotor. Higher shearing forces are produced thereby so that the air bubbles are distributed uniformly within the confectionery mass and the bubble size is reduced. The rotational speed of the rotor is controlled in response to the flow rate in accordance with empirical values. The tendency, however, is that a higher flow rate makes necessary a higher rotational speed of the rotator.

Preferably, a back-pressure valve is installed in the outlet of the aeration device. The back-pressure produced by the back-pressure valve is the pressure prevailing in the aeration device. The feed pump of the aeration device has to work against the back-pressure maintained by the back-pressure valve. The higher the back-pressure is the smaller are the bubbles produced by the aeration device. Preferably, the value of the back-pressure produced by the back-pressure valve is adjustable and the back-pressure value is controlled in response to the flow rate of the confectionery mass.

The confectionery mass is supplied from the outlet into a depositor hopper or preferably a pressurized manifold from which the aerated confectionery mass is conducted to a production line, e.g. moulds for forming the desired product. The depositor hopper includes a level indicator from which the signal indicating the demand of the production line is derived. In case of depositing via a pressurized manifold the production line includes a speed indicator from which the demand of the production line is derived.

The pressurized manifold is in general commercially available and comprises multiple nozzles, e.g. 10 to 150 nozzles, through which the aerated mass is filled into moulds which are positioned on a moulding line. The pressure of preferably 3-4 bars is maintained until the mass leaves the nozzle. Usually the moulds are overfilled and the overfilled portion of the product is scraped off. Subsequently the moulds are transported to a vibration section and vibrated in order to better distribute the product in the mould. The product is then cooled to about 16° C. and demoulded. Due to the high viscosity of the mass and the reduced time between filling and solidifying of the mass, the small bubble size of the micro-aeration process may be maintained. A further advantage of the pressurized filling is that the mechanical stress on the mass can be minimized.

In the most preferred form the apparatus includes a cascade control, including the following steps:

-   -   controlling the feed pump of the aeration device in response to         the demand of the production line;     -   controlling the gas feed rate to be a predetermined percentage         of the confectionery mass feed rate;     -   controlling the rotational speed of the rotor of the aeration         device in response to the feed rate of the confectionery mass         such that the size of the gas bubbles is below a predetermined         level;     -   controlling the pressure within the aeration device in response         to the confectionery mass feed rate;     -   controlling the cooling power such that the temperature of the         confectionery mass is in the aeration device within a         predetermined temperature range.

The rotational speed of the rotor, the pressure and the cooling power are controlled according to empirical tables by a control unit.

The parameters and the working principle are as follows for chocolate mass: The following parameters are entered into the control unit:

-   -   desired aeration level of chocolate mass (preferably         online-density)     -   chocolate mass flow     -   gas flow     -   rotational speed of rotor     -   back pressure     -   chocolate temperature         -   at the inlet of the aeration device         -   at the outlet of the aeration device     -   temperature of cooling media

Working principle:

-   based on the demand of the downstream production line the aeration     unit will either increase or decrease the throughput while ensuring     required aeration level (e.g. 10%)

Increase of chocolate mass throughput:

-   -   amount of chocolate mass and gas flow will be adjusted         accordingly to defined ratio resp. online density reading     -   increase of rotor speed     -   increase of back pressure, e.g. up to a maximum of 5-7 bar (if         the confectionery mass is a filling mass the back pressure may         be increased up to 16 bar)     -   control of temperature difference between inlet and outlet     -   in case of temperature increase of chocolate mass at the outlet         decrease of the temperature of the cooling media to maintain         initial difference     -   in case of still increasing chocolate outlet temperature while         minimum temperature for cooling media is achieved, a decrease of         rotor speed is required

Decrease of chocolate mass throughput:

-   -   amount of chocolate mass and gas flow will be adjusted         accordingly to defined ratio resp. online density reading     -   decrease of back pressure (minimum 3-4 bars)     -   decrease of rotor speed     -   control of temperature difference between inlet and outlet     -   in case of temperature increase of chocolate mass at outlet         decrease of the temperature of the cooling media to maintain         initial difference

During continuous operation no portion of the mass will be returned from the aeration unit to the mass tank. The control unit controls the feed pump of the aeration unit in order to increase or decrease the throughput of the aeration unit in accordance with the demand of the production device or line for forming the desired product.

Flow depending control of gas input, rotation speed of the rotor, back-pressure and the temperature of the aerated mass are the key working principle. Any flow variations of units operating down-stream of the aeration unit are balanced by the control unit. Back-pressure, gas input, rotation speed and temperature of the aerated mass are adjusted to ensure the desired aeration level independently of flow variations caused by units placed down-stream of the aeration unit.

The advantages obtained by the claimed invention are primarily reduced start-up time and avoidance of any recirculated masses, which would need to be de-tempered, de-aerated and re-tempered.

The invention is applicable primarily to chocolate and filling masses.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described with reference to the drawings in more details, in which:

FIG. 1 shows a first embodiment of the invention.

FIG. 2 shows a second embodiment of the invention.

FIG. 3 shows a flow diagram of the control principle which constitutes a cascade control.

FIG. 4 shows a table of the mass flow vs. pressure.

FIG. 5 shows a table of mass flow vs. rotation speed.

FIG. 6 shows a third embodiment of the invention and represents a variation of the first embodiment with a pressurized manifold.

FIG. 7 shows a fourth embodiment of the invention and represents a variation of the second embodiment with a pressurized manifold.

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 1 fresh chocolate mass is fed into a mass tank 10 at a temperature of about 45° C. The fresh chocolate mass is withdrawn from the bottom of the mass tank 10 and fed to a tempering unit 12 by a feed pump 14. The feed pump 14 is a positive displacement pump. The temperature of the chocolate mass is first decreased to about 27° C. and then raised to about 29 to 31° C. in the tempering unit 12. From the tempering unit the chocolate mass is fed to a micro-aeration unit 18. The micro-aeration unit 18 includes a stator and a rotor which is driven by a motor 20. The rotor has the form of a paddle wheel. The chocolate mass is stirred and kneaded in the micro-aeration unit 18 between the stator and the rotor and N₂ gas is added with a pressure of about 3 bar so that an aeration level of about 10% is achieved. The aerated chocolate mass is fed from the outlet 22 of the micro-aeration unit through a back-pressure regulating valve 22 into a depositor hopper 24 of a production line 32 from which the aerated chocolate mass is further processed.

A switch 26 is provided at the outlet of the micro-aeration unit 18 so that the aerated chocolate can be returned to the mass tank 10 during start-up of the system in order to drain the system. A decrystallizer 34 is arranged in this return conduit. Apart from the start-up operation, the aerated chocolate mass is not re-circulated or returned to the mass tank 10.

The depositor hopper 24 has a level detector 28. The signal of the level detector 28 indicates the demand of the production line 32. The higher the level is, the lower is the demand and vice versa. The signal of the level detector 28 is transmitted to a control unit 30 which controls the feed rate of the feed pump 14 such that the level of the confectionery mass in the depositor hopper 24 corresponds to a nominal level.

The control unit 30 controls also the pressure in the N₂ feed line such that the N₂ feed rate is proportional to the feed rate of the confectionery mass, whereby a constant aeration level in the confectionery mass delivered from the aeration device 18 is obtained.

The control unit 30 controls also the rotational speed of the rotor of the aeration unit 18 and the back-pressure adjusted by the back-pressure valve 22. These two parameters are decisive for the size of the air bubbles. A higher rotational speed of the rotor and a higher pressure in the aeration unit bring about a smaller bubble size. A higher feed rate of the feed pump 14 results in a shorter dwelling time of the confectionery mass within the aeration unit 18, which, in turn, results in a larger bubble size. A higher feed rate of the feed pump 14 has therefore to be compensated for by a higher rotational speed of the rotor and higher pressure in the aeration unit 18.

Control of the rotational speed of the rotor and of the back-pressure is preferred in order to save energy. It is possible to run the aeration device 18 continuously with the maximum rotational speed of the rotor and the maximum back-pressure, as they are necessary for a maximum feed rate of the feed pump 14. This results in an unnecessary high power consumption at lower feed rates because at lower feed rates the size of the gas bubbles will then be smaller than necessary. The size of the gas bubbles needs not to be smaller than 50 μm in order not to be visible. The smaller size of the gas bubbles does not detract from the quality of the product but is a waste of energy.

Control of the temperature is, however, important. The rotating rotator develops heat within the aeration unit. The amount of heat depends on the rotational speed of the rotator as well as on the dwelling time of the mass within the aeration unit 18, i. e. on the feed rate of the feed pump 14. The aeration unit 18 includes therefore means for controlling the temperature of the confectionery mass. The inner walls of the aeration unit 18 can include a cooling jacket or pipe through which a cooling medium like water circulates. The inlet temperature of the cooling medium and the flow rate are adjusted in order to produce the desired cooling effect. The temperature of the confectionery mass at the outlet of the aeration unit 18 is measured and transmitted to the control unit 30, which also controls the cooling equipment of the aeration unit 18.

In summary the control unit 30 constitutes a cascade control, whereas the demand of the production line 32 leads to a predetermined ratio of the gas feed rate relative to the confectionery mass feed rate. Dependent on this, the rotational speed of the rotor is adjusted. The cascade continues with an adjustment of pressure which requires changing the temperature of the cooling media adapted to the working-copy conditions.

Aeration units 18 having suitable cooling means are inter alia the models Rotoplus 3000 and Rotoplus 1000 of Tanis Food Tec and the models T-2000 and T-750 of Trefa Continu Aerating systems. FIG. 4 and FIG. 5 show the dependency of the pressure and rotation speed respectively on the mass flow for the Aeration unit T-2000 of Trefa Continu Aerating system.

The conduits between the tempering unit 12 and the dispensing nozzle of the aeration unit 18 are temperature controlled. The temperature is controlled to maintain chocolate temperature between 28 and 31 degrees centigrade when processing chocolate mass.

FIG. 2 shows an embodiment of the invention wherein the single feed pump 14 is replaced by a first and a second feed pump 15, 16. The first feed pump 15 is arranged between the mass tank 10 and the tempering unit 12 and the second feed pump 16 is arranged between the tempering unit 12 and the micro-aeration unit 18. The second feed pump 16 is a positive displacement pump and controlled in the same way as the single feed pump 14 of the first embodiment shown in FIG. 1.

FIG. 6 shows a third embodiment of the invention wherein the depositor hopper 24 of the production line is replaced by a pressurized manifold 40. The production line has a speed detector 38. The signal of the speed detector 38 indicates the demand of the production line 32. The higher the speed is, the higher is the demand and vice versa. The signal of the speed detector 38 is transmitted to a control unit 30 which controls the feed rate of the feed pump 14 such that the speed of the confectionery mass into the pressurized manifold 40 corresponds to a predetermined speed. The confectionery mass is then filled under pressure through the pressurized manifold 40 into moulds 44 which are positioned on a moulding line 42. After filling the moulds 44 with the confectionery, the moulds 44 are transported to a vibration section 46 and the moulds 44 are vibrated.

In FIG. 7 the single feed pump 14 is replaced by a first and second feed pump 15, 16 according to the embodiment shown in FIG. 2. The depositing unit is realized by a pressurized manifold 40 in accordance to FIG. 6.

LIST OF REFERENCE NUMBER

-   10 mass tanks -   12 tempering unit -   14 feed pump -   15 first feed pump -   16 second feed pump -   18 micro-aeration unit -   20 motor -   22 outlet -   24 depositor hopper -   26 switch -   28 level detector -   30 control unit -   32 production line -   34 decrystallizer -   38 speed detector -   40 pressurized manifold -   42 moulding line -   44 mould -   46 vibration section 

1-10. (canceled)
 11. A method for producing an aerated confectionery mass comprising: providing an aeration unit comprising a stator and a rotor; feeding a raw confectionery mass at a feed rate from a supply to the aeration unit; introducing gas into confectionery mass within the space between the stator and the rotor of the aeration unit; feeding the aerated confectionery mass to a production line for production of confectionery; controlling the feed rate of the raw confectionery mass according to demand of the production line; controlling amount of introduced gas in response to the feed rate of the confectionery mass so that an aeration level of the confectionery mass remains substantially constant; and controlling temperature of the mass within the aeration unit such that said mass remains substantially constant and independent from the feed rate.
 12. The method according to claim 1, comprising: stirring and kneading the confectionery mass containing the introduced gas; and controlling rotational speed of the rotor so that it is enhanced for higher feed rates and reduced for lower feed rates in order to produce gas bubbles of approximately the same size independent from the feed rate.
 13. The method according to claim 12, wherein the pressure in the aeration unit is enhanced for higher feed rates and reduced for lower feed rates.
 14. The method according to claim 13, comprising step of filling the confectionery mass under pressure into moulds of a molding line through a pressurized manifold of the production line.
 15. The method according to claim 11, wherein the confectionery mass is a chocolate mass or filling mass.
 16. The method according to claim 11, wherein the confectionery mass is a filling mass.
 17. An apparatus for producing an aerated confectionary mass, comprising: a supply for a raw confectionery mass; an aeration unit comprising a stator and a rotor wherein gas is incorporated into the confectionery mass within a space between the stator and the rotor; a feed pump for feeding the confectionery mass to the aeration unit; means for measuring amount of aerated confectionery mass demanded by a production line; means for controlling the feed rate of the feed pump according to demand of the production line; and means for controlling temperature of the confectionery mass during aeration in the aeration unit to keep the temperature substantially unchanged.
 18. The apparatus according to claim 17, comprising a depositor hopper with a level indicator which generates a signal indicating the demand of the production line, wherein the aerated confectionery mass is dispensed from the aeration unit into the depositor hopper.
 19. The apparatus according to claims 17, which the production line comprises a pressurized manifold through which the confectionary mass is filled into molds of a molding line under pressure.
 20. The apparatus according to claim 18, wherein the rotor of the aeration unit is adapted for stirring and kneading the confectionery mass containing the introduced gas, the rotational speed of the rotor being controlled by a control unit such that it is enhanced for higher feed rates and reduced for lower feed rates.
 21. The apparatus according to claim 20, comprising a back-pressure regulating valve arranged in an outlet line from the aeration unit, wherein the back-pressure generated by the valve is controlled by a control unit such that to enhance the back pressure for higher feed rates and to reduce same for lower feed rates.
 22. The apparatus according to claim 19, wherein the rotor of the aeration unit is adapted for stirring and kneading the confectionery mass containing the introduced gas, the rotational speed of the rotor being controlled by a control unit such that it is enhanced for higher feed rates and reduced for lower feed rates.
 23. The apparatus according to claim 22, comprising a back-pressure regulating valve arranged in an outlet line from the aeration unit, wherein the back-pressure generated by the valve is controlled by a control unit such that to enhance the back pressure for higher feed rates and to reduce same for lower feed rates. 